From d47af77e253e7d8dcb6d9e05d65d1b94d2dee23c Mon Sep 17 00:00:00 2001
From: Venkateshprasad <32921645+ven-k@users.noreply.github.com>
Date: Fri, 1 Dec 2023 16:52:57 +0530
Subject: [PATCH 1/5] feat: support array of components in `@mtkmodel`

- for loop or a list comprehension can be used to declare component arrays
---
 src/systems/abstractsystem.jl |   7 +-
 src/systems/model_parsing.jl  | 132 ++++++++++++++++++++++------------
 test/model_parsing.jl         |  38 ++++++++++
 3 files changed, 129 insertions(+), 48 deletions(-)

diff --git a/src/systems/abstractsystem.jl b/src/systems/abstractsystem.jl
index e37cb874c2..253565ea88 100644
--- a/src/systems/abstractsystem.jl
+++ b/src/systems/abstractsystem.jl
@@ -1402,7 +1402,7 @@ function _named(name, call, runtime = false)
     end
 end
 
-function _named_idxs(name::Symbol, idxs, call)
+function _named_idxs(name::Symbol, idxs, call; extra_args = "")
     if call.head !== :->
         throw(ArgumentError("Not an anonymous function"))
     end
@@ -1413,7 +1413,10 @@ function _named_idxs(name::Symbol, idxs, call)
     ex = Base.Cartesian.poplinenum(ex)
     ex = _named(:(Symbol($(Meta.quot(name)), :_, $sym)), ex, true)
     ex = Base.Cartesian.poplinenum(ex)
-    :($name = $map($sym -> $ex, $idxs))
+    :($name = map($sym -> begin
+            $extra_args
+            $ex
+        end, $idxs))
 end
 
 function single_named_expr(expr)
diff --git a/src/systems/model_parsing.jl b/src/systems/model_parsing.jl
index 67abc2cca9..646aa9b888 100644
--- a/src/systems/model_parsing.jl
+++ b/src/systems/model_parsing.jl
@@ -40,7 +40,7 @@ function _model_macro(mod, name, expr, isconnector)
         :kwargs => Dict{Symbol, Dict}(),
         :structural_parameters => Dict{Symbol, Dict}()
     )
-    comps = Symbol[]
+    comps = Union{Symbol, Expr}[]
     ext = Ref{Any}(nothing)
     eqs = Expr[]
     icon = Ref{Union{String, URI}}()
@@ -745,7 +745,7 @@ end
 
 ### Parsing Components:
 
-function component_args!(a, b, expr, varexpr, kwargs)
+function component_args!(a, b, varexpr, kwargs; index_name = nothing)
     # Whenever `b` is a function call, skip the first arg aka the function name.
     # Whenever it is a kwargs list, include it.
     start = b.head == :call ? 2 : 1
@@ -754,73 +754,115 @@ function component_args!(a, b, expr, varexpr, kwargs)
         arg isa LineNumberNode && continue
         MLStyle.@match arg begin
             x::Symbol || Expr(:kw, x) => begin
-                _v = _rename(a, x)
-                b.args[i] = Expr(:kw, x, _v)
-                push!(varexpr.args, :((@isdefined $x) && ($_v = $x)))
-                push!(kwargs, Expr(:kw, _v, nothing))
-                # dict[:kwargs][_v] = nothing
+                varname, _varname = _rename(a, x)
+                b.args[i] = Expr(:kw, x, _varname)
+                push!(varexpr.args, :((if $varname !== nothing
+                    $_varname = $varname
+                elseif @isdefined $x
+                    # Allow users to define a var in `structural_parameters` and set
+                    # that as positional arg of subcomponents; it is useful for cases
+                    # where it needs to be passed to multiple subcomponents.
+                    $_varname = $x
+                end)))
+                push!(kwargs, Expr(:kw, varname, nothing))
+                # dict[:kwargs][varname] = nothing
             end
             Expr(:parameters, x...) => begin
-                component_args!(a, arg, expr, varexpr, kwargs)
+                component_args!(a, arg, varexpr, kwargs)
             end
             Expr(:kw, x, y) => begin
-                _v = _rename(a, x)
-                b.args[i] = Expr(:kw, x, _v)
-                push!(varexpr.args, :($_v = $_v === nothing ? $y : $_v))
-                push!(kwargs, Expr(:kw, _v, nothing))
-                # dict[:kwargs][_v] = nothing
+                varname, _varname = _rename(a, x)
+                b.args[i] = Expr(:kw, x, _varname)
+                if isnothing(index_name)
+                    push!(varexpr.args, :($_varname = $varname === nothing ? $y : $varname))
+                else
+                    push!(varexpr.args,
+                        :($_varname = $varname === nothing ? $y : $varname[$index_name]))
+                end
+                push!(kwargs, Expr(:kw, varname, nothing))
+                # dict[:kwargs][varname] = nothing
             end
             _ => error("Could not parse $arg of component $a")
         end
     end
 end
 
-function _parse_components!(exprs, body, kwargs)
-    expr = Expr(:block)
+model_name(name, range) = Symbol.(name, :_, collect(range))
+
+function _parse_components!(body, kwargs)
+    local expr
     varexpr = Expr(:block)
-    # push!(exprs, varexpr)
-    comps = Vector{Union{Symbol, Expr}}[]
+    comps = Vector{Union{Union{Expr, Symbol}, Expr}}[]
     comp_names = []
 
-    for arg in body.args
-        arg isa LineNumberNode && continue
-        MLStyle.@match arg begin
-            Expr(:block) => begin
-                # TODO: Do we need this?
-                error("Multiple `@components` block detected within a single block")
-            end
-            Expr(:(=), a, b) => begin
-                arg = deepcopy(arg)
-                b = deepcopy(arg.args[2])
+    Base.remove_linenums!(body)
+    arg = body.args[end]
+
+    MLStyle.@match arg begin
+        Expr(:(=), a, Expr(:comprehension, Expr(:generator, b, Expr(:(=), c, d)))) => begin
+            array_varexpr = Expr(:block)
 
-                component_args!(a, b, expr, varexpr, kwargs)
+            push!(comp_names, :($a...))
+            push!(comps, [a, b.args[1], d])
+            b = deepcopy(b)
 
-                arg.args[2] = b
-                push!(expr.args, arg)
-                push!(comp_names, a)
+            component_args!(a, b, array_varexpr, kwargs; index_name = c)
+
+            expr = _named_idxs(a, d, :($c -> $b); extra_args = array_varexpr)
+        end
+        Expr(:(=), a, Expr(:comprehension, Expr(:generator, b, Expr(:filter, e, Expr(:(=), c, d))))) => begin
+            error("List comprehensions with conditional statements aren't supported.")
+        end
+        Expr(:(=), a, Expr(:comprehension, Expr(:generator, b, Expr(:(=), c, d), e...))) => begin
+            # Note that `e` is of the form `Tuple{Expr(:(=), c, d)}`
+            error("More than one index isn't supported while building component array")
+        end
+        Expr(:block) => begin
+            # TODO: Do we need this?
+            error("Multiple `@components` block detected within a single block")
+        end
+        Expr(:(=), a, Expr(:for, Expr(:(=), c, d), b)) => begin
+            Base.remove_linenums!(b)
+            array_varexpr = Expr(:block)
+            push!(array_varexpr.args, b.args[1:(end - 1)]...)
+            push!(comp_names, :($a...))
+            push!(comps, [a, b.args[end].args[1], d])
+            b = deepcopy(b)
+
+            component_args!(a, b.args[end], array_varexpr, kwargs; index_name = c)
+
+            expr = _named_idxs(a, d, :($c -> $(b.args[end])); extra_args = array_varexpr)
+        end
+        Expr(:(=), a, b) => begin
+            arg = deepcopy(arg)
+            b = deepcopy(arg.args[2])
+
+            component_args!(a, b, varexpr, kwargs)
+
+            arg.args[2] = b
+            expr = :(@named $arg)
+            push!(comp_names, a)
                 if (isa(b.args[1], Symbol) || Meta.isexpr(b.args[1], :.))
-                    push!(comps, [a, b.args[1]])
+                push!(comps, [a, b.args[1]])
                 end
-            end
-            _ => error("Couldn't parse the component body: $arg")
         end
+        _ => error("Couldn't parse the component body: $arg")
     end
+
     return comp_names, comps, expr, varexpr
 end
 
 function push_conditional_component!(ifexpr, expr_vec, comp_names, varexpr)
     blk = Expr(:block)
     push!(blk.args, varexpr)
-    push!(blk.args, :(@named begin
-        $(expr_vec.args...)
-    end))
+    push!(blk.args, expr_vec)
     push!(blk.args, :($push!(systems, $(comp_names...))))
     push!(ifexpr.args, blk)
 end
 
 function handle_if_x!(mod, exprs, ifexpr, x, kwargs, condition = nothing)
     push!(ifexpr.args, condition)
-    comp_names, comps, expr_vec, varexpr = _parse_components!(ifexpr, x, kwargs)
+    comp_names, comps, expr_vec, varexpr = _parse_components!(x, kwargs)
     push_conditional_component!(ifexpr, expr_vec, comp_names, varexpr)
     comps
 end
@@ -836,7 +878,7 @@ function handle_if_y!(exprs, ifexpr, y, kwargs)
         push!(ifexpr.args, elseifexpr)
         (comps...,)
     else
-        comp_names, comps, expr_vec, varexpr = _parse_components!(exprs, y, kwargs)
+        comp_names, comps, expr_vec, varexpr = _parse_components!(y, kwargs)
         push_conditional_component!(ifexpr, expr_vec, comp_names, varexpr)
         comps
     end
@@ -861,25 +903,23 @@ function parse_components!(exprs, cs, dict, compbody, kwargs)
             Expr(:if, condition, x, y) => begin
                 handle_conditional_components(condition, dict, exprs, kwargs, x, y)
             end
-            Expr(:(=), a, b) => begin
-                comp_names, comps, expr_vec, varexpr = _parse_components!(exprs,
-                    :(begin
+            # Either the arg is top level component declaration or an invalid cause - both are handled by `_parse_components`
+            _ => begin
+                comp_names, comps, expr_vec, varexpr = _parse_components!(:(begin
                         $arg
                     end),
                     kwargs)
                 push!(cs, comp_names...)
                 push!(dict[:components], comps...)
-                push!(exprs, varexpr, :(@named begin
-                    $(expr_vec.args...)
-                end))
+                push!(exprs, varexpr, expr_vec)
             end
-            _ => error("Couldn't parse the component body $compbody")
         end
     end
 end
 
 function _rename(compname, varname)
     compname = Symbol(compname, :__, varname)
+    (compname, Symbol(:_, compname))
 end
 
 # Handle top level branching
diff --git a/test/model_parsing.jl b/test/model_parsing.jl
index 706b97c598..851aa33aab 100644
--- a/test/model_parsing.jl
+++ b/test/model_parsing.jl
@@ -650,3 +650,41 @@ end
 @named m = MyModel()
 @variables x___(t)
 @test isequal(x___, _b[])
+
+@testset "Component array" begin
+    @mtkmodel SubComponent begin
+        @parameters begin
+            sc
+        end
+    end
+
+    @mtkmodel Component begin
+        @structural_parameters begin
+            N = 2
+        end
+        @components begin
+            comprehension = [SubComponent(sc = i) for i in 1:N]
+            written_out_for = for i in 1:N
+                sc = i + 1
+                SubComponent(; sc)
+            end
+            single_sub_component = SubComponent()
+        end
+    end
+
+    @named component = Component()
+    component = complete(component)
+
+    @test nameof.(ModelingToolkit.get_systems(component)) == [
+        :comprehension_1,
+        :comprehension_2,
+        :written_out_for_1,
+        :written_out_for_2,
+        :single_sub_component,
+    ]
+
+    @test getdefault(component.comprehension_1.sc) == 1
+    @test getdefault(component.comprehension_2.sc) == 2
+    @test getdefault(component.written_out_for_1.sc) == 2
+    @test getdefault(component.written_out_for_2.sc) == 3
+end

From 86d345fbf4c7b35c2fbcc5797b88ab5e9d53065a Mon Sep 17 00:00:00 2001
From: Venkateshprasad <32921645+ven-k@users.noreply.github.com>
Date: Fri, 1 Dec 2023 16:45:45 +0530
Subject: [PATCH 2/5] docs: add component array in the docs

---
 docs/src/basics/MTKModel_Connector.md | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/docs/src/basics/MTKModel_Connector.md b/docs/src/basics/MTKModel_Connector.md
index c9fc0bcb60..ef17518ff4 100644
--- a/docs/src/basics/MTKModel_Connector.md
+++ b/docs/src/basics/MTKModel_Connector.md
@@ -58,6 +58,7 @@ end
     end
     @structural_parameters begin
         f = sin
+        N = 2
     end
     begin
         v_var = 1.0
@@ -69,6 +70,11 @@ end
     @extend ModelB(; p1)
     @components begin
         model_a = ModelA(; k_array)
+        model_array_a = [ModelA(; k = i) for i in 1:N]
+        model_array_b = for i in 1:N
+            k = i^2
+            ModelA(; k)
+        end
     end
     @equations begin
         model_a.k ~ f(v)
@@ -146,6 +152,7 @@ julia> @mtkbuild model_c2 = ModelC(; p1 = 2.0)
 #### `@components` begin block
 
   - Declare the subcomponents within `@components` begin block.
+  - Array of components can be declared with a for loop or a list comprehension.
   - The arguments in these subcomponents are promoted as keyword arguments as `subcomponent_name__argname` with `nothing` as default value.
   - Whenever components are created with `@named` macro, these can be accessed with `.` operator as `subcomponent_name.argname`
   - In the above example, as `k` of `model_a` isn't listed while defining the sub-component in `ModelC`, its default value can't be modified by users. While `k_array` can be set as:
@@ -223,7 +230,7 @@ end
 ```
 
 !!! note
-    
+
     For more examples of usage, checkout [ModelingToolkitStandardLibrary.jl](https://github.com/SciML/ModelingToolkitStandardLibrary.jl/)
 
 ## More on `Model.structure`
@@ -247,14 +254,13 @@ For example, the structure of `ModelC` is:
 ```julia
 julia> ModelC.structure
 Dict{Symbol, Any} with 9 entries:
-  :components            => Any[Union{Expr, Symbol}[:model_a, :ModelA]]
+  :components            => Any[Union{Expr, Symbol}[:model_a, :ModelA], Union{Expr, Symbol}[:model_array_a, :ModelA, :(1:N)], Union{Expr, Symbol}[:model_array_b, :ModelA, :(1:N)]]
   :variables             => Dict{Symbol, Dict{Symbol, Any}}(:v=>Dict(:default=>:v_var, :type=>Real), :v_array=>Dict(:type=>Real, :size=>(2, 3)))
   :icon                  => URI("https://github.com/SciML/SciMLDocs/blob/main/docs/src/assets/logo.png")
-  :constants             => Dict{Symbol, Dict}(:c=>Dict{Symbol, Any}(:value=>1, :type=>Int64, :description=>"Example constant."))
-  :kwargs                => Dict{Symbol, Dict}(:f=>Dict(:value=>:sin), :v=>Dict{Symbol, Union{Nothing, Symbol}}(:value=>:v_var, :type=>Real), :v_array=>Dict(:value=>nothing, :type=>Real), :p1=>Dict(:value=>nothing))
-  :structural_parameters => Dict{Symbol, Dict}(:f=>Dict(:value=>:sin))
+  :kwargs                => Dict{Symbol, Dict}(:f=>Dict(:value=>:sin), :N=>Dict(:value=>2), :v=>Dict{Symbol, Any}(:value=>:v_var, :type=>Real), :v_array=>Dict{Symbol, Union{Nothing, UnionAll}}(:value=>nothing, :type=>AbstractArray{Real}), :p1=>Dict(:value=>nothing))
+  :structural_parameters => Dict{Symbol, Dict}(:f=>Dict(:value=>:sin), :N=>Dict(:value=>2))
   :independent_variable  => t
-  :constants             => Dict{Symbol, Dict}(:c=>Dict(:value=>1))
+  :constants             => Dict{Symbol, Dict}(:c=>Dict{Symbol, Any}(:value=>1, :type=>Int64, :description=>"Example constant."))
   :extend                => Any[[:p2, :p1], Symbol("#mtkmodel__anonymous__ModelB"), :ModelB]
   :equations             => Any["model_a.k ~ f(v)"]
 ```

From 53fabfc2b9e72a9a4b0300ecd7d57619e17f4937 Mon Sep 17 00:00:00 2001
From: Venkateshprasad <32921645+ven-k@users.noreply.github.com>
Date: Mon, 4 Dec 2023 18:53:11 +0530
Subject: [PATCH 3/5] feat: extend `Base.parentmodule` for `Model`

---
 src/systems/model_parsing.jl |  2 ++
 test/model_parsing.jl        | 12 ++++++++++++
 2 files changed, 14 insertions(+)

diff --git a/src/systems/model_parsing.jl b/src/systems/model_parsing.jl
index 646aa9b888..7409601a9e 100644
--- a/src/systems/model_parsing.jl
+++ b/src/systems/model_parsing.jl
@@ -24,6 +24,8 @@ struct Model{F, S}
 end
 (m::Model)(args...; kw...) = m.f(args...; kw...)
 
+Base.parentmodule(m::Model) = parentmodule(m.f)
+
 for f in (:connector, :mtkmodel)
     isconnector = f == :connector ? true : false
     @eval begin
diff --git a/test/model_parsing.jl b/test/model_parsing.jl
index 851aa33aab..3d6da78eab 100644
--- a/test/model_parsing.jl
+++ b/test/model_parsing.jl
@@ -688,3 +688,15 @@ end
     @test getdefault(component.written_out_for_1.sc) == 2
     @test getdefault(component.written_out_for_2.sc) == 3
 end
+
+module GetParentModule
+
+using ModelingToolkit
+
+@mtkmodel Component begin end
+
+end
+
+@testset "Parent module of Models" begin
+    @test parentmodule(GetParentModule.Component) == GetParentModule
+end

From a4a79ce18e45d1b4b6762c4a7cf5f7151d3cb8a2 Mon Sep 17 00:00:00 2001
From: Venkateshprasad <32921645+ven-k@users.noreply.github.com>
Date: Mon, 26 Feb 2024 10:16:58 +0530
Subject: [PATCH 4/5] test: use MyMockModule for testing parent-module

---
 test/model_parsing.jl | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/test/model_parsing.jl b/test/model_parsing.jl
index 3d6da78eab..dafe46d388 100644
--- a/test/model_parsing.jl
+++ b/test/model_parsing.jl
@@ -689,14 +689,6 @@ end
     @test getdefault(component.written_out_for_2.sc) == 3
 end
 
-module GetParentModule
-
-using ModelingToolkit
-
-@mtkmodel Component begin end
-
-end
-
 @testset "Parent module of Models" begin
-    @test parentmodule(GetParentModule.Component) == GetParentModule
+    @test parentmodule(MyMockModule.Ground) == MyMockModule
 end

From e32463355a90ee09d6270515fe6dcf2392d1098b Mon Sep 17 00:00:00 2001
From: Venkateshprasad <32921645+ven-k@users.noreply.github.com>
Date: Mon, 4 Mar 2024 12:20:31 +0530
Subject: [PATCH 5/5] test: conditionally define component array

---
 docs/src/basics/MTKModel_Connector.md |  2 +-
 src/systems/model_parsing.jl          |  4 ++--
 test/model_parsing.jl                 | 29 ++++++++++++++++++++++++++-
 3 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/docs/src/basics/MTKModel_Connector.md b/docs/src/basics/MTKModel_Connector.md
index ef17518ff4..d4b81e32ff 100644
--- a/docs/src/basics/MTKModel_Connector.md
+++ b/docs/src/basics/MTKModel_Connector.md
@@ -230,7 +230,7 @@ end
 ```
 
 !!! note
-
+    
     For more examples of usage, checkout [ModelingToolkitStandardLibrary.jl](https://github.com/SciML/ModelingToolkitStandardLibrary.jl/)
 
 ## More on `Model.structure`
diff --git a/src/systems/model_parsing.jl b/src/systems/model_parsing.jl
index 7409601a9e..7ee74e5dc1 100644
--- a/src/systems/model_parsing.jl
+++ b/src/systems/model_parsing.jl
@@ -844,9 +844,9 @@ function _parse_components!(body, kwargs)
             arg.args[2] = b
             expr = :(@named $arg)
             push!(comp_names, a)
-                if (isa(b.args[1], Symbol) || Meta.isexpr(b.args[1], :.))
+            if (isa(b.args[1], Symbol) || Meta.isexpr(b.args[1], :.))
                 push!(comps, [a, b.args[1]])
-                end
+            end
         end
         _ => error("Couldn't parse the component body: $arg")
     end
diff --git a/test/model_parsing.jl b/test/model_parsing.jl
index dafe46d388..ae3ec193b3 100644
--- a/test/model_parsing.jl
+++ b/test/model_parsing.jl
@@ -680,13 +680,40 @@ end
         :comprehension_2,
         :written_out_for_1,
         :written_out_for_2,
-        :single_sub_component,
+        :single_sub_component
     ]
 
     @test getdefault(component.comprehension_1.sc) == 1
     @test getdefault(component.comprehension_2.sc) == 2
     @test getdefault(component.written_out_for_1.sc) == 2
     @test getdefault(component.written_out_for_2.sc) == 3
+
+    @mtkmodel ConditionalComponent begin
+        @structural_parameters begin
+            N = 2
+        end
+        @components begin
+            if N == 2
+                if_comprehension = [SubComponent(sc = i) for i in 1:N]
+            elseif N == 3
+                elseif_comprehension = [SubComponent(sc = i) for i in 1:N]
+            else
+                else_comprehension = [SubComponent(sc = i) for i in 1:N]
+            end
+        end
+    end
+
+    @named if_component = ConditionalComponent()
+    @test nameof.(get_systems(if_component)) == [:if_comprehension_1, :if_comprehension_2]
+
+    @named elseif_component = ConditionalComponent(; N = 3)
+    @test nameof.(get_systems(elseif_component)) ==
+          [:elseif_comprehension_1, :elseif_comprehension_2, :elseif_comprehension_3]
+
+    @named else_component = ConditionalComponent(; N = 4)
+    @test nameof.(get_systems(else_component)) ==
+          [:else_comprehension_1, :else_comprehension_2,
+        :else_comprehension_3, :else_comprehension_4]
 end
 
 @testset "Parent module of Models" begin